Chocolate derives its desirable eating qualities largely from the melting properties of cocoa butter which is typically present at 25-35% by weight. At room temperature (70.degree.-74.degree. F., 21.1.degree.-23.3.degree. C.) cocoa butter is a firm solid. Firmness is desirable not only to provide "snap" at initial bite, but also to resist deformation and surface marking of the chocolate from time of manufacture to time of consumption.
Above room temperature, cocoa butter melts progressively until it is fully melted near 93.degree.-94.degree. F. (33.9.degree.-34.4.degree. C.), and is therefore entirely liquid below body temperature (98.6.degree. F., 37.degree. C.). This rapid melting at mouth temperature ("mouthmelt") provides a smooth, creamy consistency during eating and insures rapid release of chocolate flavors to the mouth. The relatively sharp melting behavior just a few degrees below body temperature is unique to cocoa butter among natural fats.
The melting behavior of cocoa butter is the result of its unique triglyceride composition. However, this unique triglyceride composition, like the triglyceride composition of other natural fats, is relatively high in calories. Approximately 50% of the calories in chocolate products come from the fat which is exclusively or predominantly cocoa butter. This means that persons who must restrict their intake of calories must either reduce the amount of chocolate products they consume, or in the extreme case, completely exclude such products from their diet. Accordingly, it would be desirable to be able to replace all or a portion of the cocoa butter present in such chocolate products with a substitute fat having fewer calories, while maintaining the desirable physical properties of cocoa butter in chocolate products.
The selection of a reduced calorie substitute fat for cocoa butter is not straightforward. First, the substitute fat must be less efficiently absorbed and/or metabolized by the body in order to exhibit a lower caloric density. Second, the substitute fat should temper and crystallize into a solid form that is very sharp melting and has mouth-melt characteristics the same, or similar, as those of cocoa butter, or combinations of cocoa butter and milkfat, present in confectionery products. Third, the crystalline form of the substitute fat should be stable under typical conditions of confectionery product distribution and handling without any significant change in the mouthmelt characteristics or appearance of the substitute fat-containing confectionery product. Such undesirable changes include the development of a waxy or grainy mouthfeel and the development of bloom, i.e. a whitish or grayish discoloration visible on the surface, or sometimes in the interior, of the confectionery product. These changes can be caused by the growth of excessively large fat crystals, the transformation of the fat crystals into a higher melting polymorphic form, the presence of too high a level of lower-melting fatty components, or incompatibility between the substitute fat and other fats present in the confectionery product, in particular cocoa butter that is typically present in the chocolate liquor and/or cocoa powder used to impart a chocolate flavoring to such products. Lastly, the substitute fat should be processable in current commercial operations used to make confectionery products.
One reduced calorie fat that has been found to be useful as a cocoa butter substitute comprises a fairly high level (e.g., at least about 85%) of combined MML and MLM triglycerides, where M is typically a mixture of C.sub.8 and C.sub.10 saturated fatty acids and L is predominantly behenic acid. See Ehrman et al. U.S. Pat. No. 4,888,196, issued Dec. 9, 1989. Unlike other cocoa butter replacers, this reduced calorie cocoa butter substitute fat exhibits polymorphism and needs to be tempered or precrystallized and then crystallized into its stable .beta.-3 crystalline phase, just as cocoa butter does. However, if chocolate products based on this reduced-calorie cocoa butter substitute fat are tempered using typical equipment and conditions suitable for cocoa butter-based chocolate products (i.e. rapidly cooling to about 82.degree. to 86.degree. F. (27.8.degree. to 30.0.degree. C.) and then warming to about 88.degree. to 93.degree. F. (31.1.degree. to 33.9.degree. C.), the products do not harden sufficiently when cooled to be wrapped or otherwise packaged, nor shrink sufficiently in molds to be easily demolded with glossy appearance, and will develop bloom.
The Ehrman et al. patent discloses an alternative tempering process for obtaining flavored confectionery products using this reduced calorie cocoa butter substitute fat. This tempering process involves rapidly cooling the flavored confectionery composition to a temperature of about 57.degree. (13.9.degree. C.) or less. This cooled composition is then held at this temperature for at least about 16 hours, which is sufficient to form, or nucleate, an effective amount of .beta.-3 crystals from a portion of the reduced calorie cocoa butter substitute fat. The cooled composition is then warmed to a temperature in the range of from about 57.degree. to about 72.degree. F. (about 13.9.degree. to about 22.2.degree. C.) to transform the remaining portion of the reduced calorie cocoa butter substitute fat into the stable .beta.-3 crystalline phase, in about 4 to about 120 hours.
Using the tempering scheme disclosed in the Ehrman et al. patent, it typically takes from about 1 to about 3 days after preparing the molten chocolate mass to obtain chocolate-flavored products which are stable against resulting bloom formation, especially when subjected to thermal stress. Accordingly, it would be desirable to develop a process for preparing chocolate-flavored confectionery compositions containing these reduced calorie cocoa butter substitute fats that does not require a prolonged tempering scheme according to the Ehrman et al. patent to provide a bloom-stable .beta.-3 phase. In particular, it would be desirable to develop a process for preparing these reduced calorie chocolate-flavored confectionery compositions that can be more easily adapted to standard manufacturing and packaging processes used in commercial cocoa butter-based chocolate operations.